Prevalence and susceptibility of salmonella Typhi and salmonella paratyphi in Zaria, Nigeria

Purpose: To investigate the prevalence and susceptibility pattern of S. typhi and S. paratyhpi isolates in Zaria. Methods: Blood samples collected from presumptive typhoid fever patients from Ahmadu Bello University (ABU), Federal College of Education (FCE) and presumptive typhoid fever patients that attended two private clinics (Salama Clinics and Savanna Polyclinics) in Zaria were cultured for Salmonella species and identified by standard procedures. The susceptibility of the isolated organisms to ten antibiotics and the minimum inhibitory concentrations were determined using the methods of the National Committee for Clinical Laboratory Standards. Results: Salmonella species infection rate at FCE, ABU, Salama Clnics and Savanna Polyclinic were 9.3%, 16.5%, 12.4%, and 17.2%, respectively. 102 Salmonella species (71 S. typhi, 15 S. paratyphi A and 16 S. paratyphi B) were isolated. Unlike ofloxacin and nalidixic acid, there was high resistance (60-100%) of the organisms to ampicillin, amoxicillin, Augumentin, chloramphenicol, co-trimoxazole, gentamicin, nitrofurantoin, and tetracycline. The order of susceptibility was ofloxacin > nalidixic acid > nitrofurantoin > co-trimoxazole > chloramphenicol > gentamicin > tetracycline > amoxicillin >ampicillin > Augumentin. Resistance profile of Salmonella species isolated from patients at ABU and FCE were significantly higher than those of the private clinics. Conclusion: Many antibiotics previously used to treat typhoid fever are no longer effective. Laboratory tests should therefore be a major consideration in the choice of antibiotics for treatment of typhoid fever.